1. Field of the Invention
The present invention relates to a portable power bank device and in particular to a portable power bank device which is easy to carry and can supply power to other electronic devices anytime.
2. Description of Prior Art
As for current various portable electronic products such as smart phones and tablet computers, due to more and more emphases on the fast and humanization design applications, the products are designed with many high-end processors and sensing elements. These elements consume lots of power energy during operation, in which the power supplement becomes required
There are two types of charging currently for electronic products. One is to use a transmission line connected directly to the electronic products to charge the internal batteries thereof; another is to take the batteries out of the electronic products first and then use a battery charger to charge the batteries. Both are transforming the voltage of the mains into a specific voltage level by means of the charger to charge the battery. However, for an outdoor user, when the power of these electronic products is exhausted, the charging power supply is not available anytime. Further, for the closed system electronic products such as an iphone or an ipad, the batteries can not be taken out for charging, which is not convenient to charge using a transmission line.
Furthermore, for such portable electronic products such as smart phones or tablet computers, equipped with a generally small screen, if many persons want to check the contents on the screen at the same time, it appears to be too crowded. The invention of mini-projectors, or called micro projectors, could solve the above problem. The currently available micro projector can be installed in the smart phone or an independent micro projector can be connected to the smart phone and then displays the images of the smart phone on the large external screen.
However, such a smart phone or a micro projector suffers from high power consumption and can not operate for a long time.